Adjustable t square



Patented Sept. 14, 1926.

ZSIVKO Gr. LAZAREVICE, OF SAN FRANCISCG, CALIFGRNIA.

ADJUSTABLE T SQUARE.

Application filed September 2, 1924. Serial No. 735,439.

Vl`hc present invention relates to improvements in Termales, and its particular object to provide an adjustable "lsquare wliiclnwhile substantial and rugged in construction, is extremely simple and can be n'ianufaetured at low cost. .lt is particularly contemplated to pivotally connect the conventional blade to the head of a nlsquare ry means of a disc secured. to one of the members and a ring element secured to `the other member allowing the disc to revolve therein. It is further proposed to utilize the simple arrangement for providing a lviaduation scale on either the ring or the dise and a pointer on the other' member allowing the angular' relation of the blade relative to the head to be easily determined. lt is further proposed to form the disc and the ring for interlocking relation so as to hold the members against axial motion and to furthermore form the two members in such a manner that the engagement does not interfere with the turning of the blade, at least, through an angle of 180 degrees. Further object-s and advantages of my device will appear as the specification pro- Coeds.

rlhe ,n'eferred form of my invention is illustrated in the accompanying drawing in.

which Figure l shows the head end of the T square in plan, Figure 2 the same device in section taken along line ll-ll of lligure l, Figure 3 an end view of the ring element used in the device shown in Figure l, Figure Il a plan View of the same, Figure 5 a plan view of the head end of a modilied .form of my T-square and Figure (S al section through 'the same taken along theV line Vl-Vl of ligure 5.

llhile l have shown only the preferred forms of the invention, it should be understood that various changes or modifications may be made within the scope of tle Claim hereto attached without departing from the spirit of the intention.

Referring first to the form shown in Figures l to d, it appears that the head piece l is of conventional forni and presents a straight edge 2 adapted to be placed against the edge of a drawing` board, not shown in the drawing. A blade 3 of conventional forni, a portion only of which is shown in the drawing, is rounded at its end, as shown at 4, and has a disc 5, preferably made of metal, secured thereto in concentric relation with its rounded end, the disc being either glued to the blade or fastened thereto by means of small screws 6. A small, preferably circular, plate 7 is secured to the underside of the head piece l by means of screws 8. the head piece I neferably being recessed, as shown in Fig. 2, to accommodate the plate and to allow the lower face thereof to be flush with the lower face of the head piece. The pin 9 extends upwardly from the plate 7 through the head piece and the blade 3 and the disc 5 are perforated in the center of the disc for pivotal engagement with the pin, a wing nut 10 threadedly engaging the top end of the Apin 9 for tightening the disc of the blade upon the head piece.

While this arrangement in itself would hold the blade to the head piece, l provide as a further means for preventing shifting of the blade relative to the head piece, the ring element ll formed for revolving engagement with the disc 5 adapted to be secured to the head pieee by means of screws 12. rlhe ring element is r cessed in its undersurface, as shown at 13 along a straight line lll, so as to allow of turning motion of the blade 8 through an angle of 180 degrees. llVhile it is not necessary that the ring element be made a complete ring, l preferably allow the arms thereof to eX- tend slightly beyond a semi-circle, as shown at l5, so that the disc is held against endwise motion .by the ring, irrespective of the holding engagement of the pin Si. The edge 4l of the blade extends beyond the dimensions of the dise and is in interlocking engagement with the undcrface of the ring so as to prevent axial motion of the blade 3 even after the wing .nut l0 has been removed.

Either the disc or the ring element is provided with a graduated scale, as shown at 16 and a pointer graduation 17 on the other element allows an angular relation of the blade relative to the head piece to be read from the scale.

To assemble the T-square, it is only neoessary to engage the blade and disc with the pin 9 and to screw the wing nut lO down upon the pin and to thereafter secure the ring element l1 in place, whereupon the blade may be freely swung about its pivot within a range of 180 degrees and fastened in any position desired by a. further tight ening of the wing nut l0. ln the form' shown in Figures 5 and G, the disc 18 is lll) secured te the head piece by means of screws 19 while the ring` element 2l forms an integral part of the blade 22. As appears from the Cross Section shown in Figure 6, the ring element and the dise are inter- .loeled by means of a tongue and groove arrangement 23 so that when the dise is fastened to the head piece by means of the screw 1.9, the blade is firmly held against endwse as Well as axial motion, but remains i'ree to revolve upon the dise. A graduation scale 2l is provided upon either ring' or die@ and a pointer :'25 on the other element in adjacent relation to the seale.

claim:

An adjustable T-square comprising a head member, a blade member pivotally and detaehably mounted on the head member, a circular disk member secured on the upper surface of the blade member adjacent the head member and adapted to turn with the blade member, said circular disk member being;1 set in from that end of the blade member which is adjacent the head member, and an element secured to the head member, said element having` a scale thereon and lravingl an arcuate edge contacting with the arcuate edge of said eireular disk member7 the areuate edge of said element being greater than a semi-circle, said element being` eut away on its underside to allow the blade member to Swing.

ZSVKO G. LAZREVCH.. 

